It's not a matter of technical complexity. It's a model thing, and a logical complexity. As it stands today, background is about the box (physical). Additionally, the gradient is a type of image -- unaffected by writing modes, transforms, or any other of the new fun toys that aren't stable specs yet.
I think it's an absolute horrid idea to intermingle these properties just because it's fun to mix the new chemicals in a beaker to see what happens.
I don't have the bandwidth right now to go into more detail, but the short version is: adding this new interaction is a bad idea. There have been a number of bad ideas in CSS that have had to be reserved, and people lament later. I'm calling this one out before it happens -- do with that what you will.
-----Original Message-----
From: Tab Atkins Jr. [mailto:jackalmage@gmail.com]
Sent: Friday, August 12, 2011 3:32 PM
To: Brad Kemper
Cc: Brian Manthos; Florian Rivoal; www-style@w3.org
Subject: Re: [css3-images] new side-or-corner keywords?
On Fri, Aug 12, 2011 at 3:30 PM, Brad Kemper <brad.kemper@gmail.com> wrote:
> I still don't understand. It seems simple enough on the surface to be able to determine e.g. what the 'start' side is, translate it to a physical side and proceed as normal.
>
> Or do you mean implementation-wise it is hard to track the value throughout the background and into the image?
>
> So far this is only about affecting the direction within the gradient itself, and not about affecting background property values such as 'background-position'. Does that make it harder to track?
Indeed. It doesn't seem particularly harder to do this than it would be to track logical keywords in any other property, like text-align.
~TJ